1. Field of the Invention
The present invention relates to a plasma measurement device, a plasma system and a method for measuring plasma characteristics. More particularly, the present invention relates to a plasma measurement device, a plasma system and a method for measuring plasma characteristics by utilizing a standing wave effect to eliminate high-frequency interference generated by the radio frequency plasma.
2. Description of the Related Art
Generally, a single-electrode Langmuir probe utilizes a tiny-surface-area metal electrode as a signal extraction tool. The probe is placed in a plasma system and is connected to a voltage supply system. By operating the voltage supply system and providing a frequency-sweep potential to the probe (such as providing adjustable direct-current voltages from −50V to 50V to the probe), the probe can extract current signals according to different potentials of its own. By depicting measured voltage-current results, a voltage-current characteristic curve can be obtained, and plasma characteristics (such as an electron temperature or an electron density) can therefore be calculated. However, the measured voltage-current curve would be distorted due to high-frequency interference.
In known prior arts, a compensation circuit is added to the circuit of the single-electrode Langmuir probe to reduce the influence from high-frequency signals. However, this kind of implementation cannot be done without a circuit design, which causes inconvenience to those who are not familiar with circuit designs.
Therefore, there is a need to provide a plasma measurement device, a plasma system, and a method for measuring plasma characteristics to mitigate and/or obviate the aforementioned problems.